Lead alloy



, Patented Feb. 5, 1946 UNITED STATES PATENT OFFICE LEAD ALLOY Edward G.Hollman, Joplin, Mo., asslgnor to The Eagle-Picher Company, Cincinnati,Ohio, a corporation of Ohio N Drawing. Application April 15, 1944,Serial No. 531,291

2 Claims. (Cl. 75-167) have long been sought in order to increase itsmechanical strength and at the same time-reduce the considerable weightwhich attends Diping installations of pure lead. By the practice of thisinvention the wall thickness of lead pipe can be materially reducedwhile its strength is increased. I have found that while magnesium is avery desirable strength conferring and hardening agent especially whenstabilized with tin its allow with lead is subject to deterioration. Theproblem is to inhibit corrosion of such an alloy so that it will retainits high strength for many years of service.

Manganese has been found to be a suitable corrosion inhibitor. alloyembodying these constituents isgiven below. The figures show thebursting strength in pounds per square inch on extruded tubing which hada wall thickness of .090" and an inside diameter of /3". Analysis byweight: Mg, .057%; Sn, 25%; Mn, .024%; Pb, Balance; bursting strength,880 p. s. i.

Accelerated corrosion tests on the Pipe showed that in corrosionresistance .after 60 days, the alloy is equal to lead, it shows no morecorrosion than other alloys now on the market for this purpose but isconsiderably stronger. These tests were made-b7 passing an alternatingcurrent of Anexample of the preferred i. e. manganese. The balance ofthe alloy is, of

course, lead.

When I extrude pipe from these alloys, I find it essential to do sounder the following conditions: We fill the cylinder of the press withany of my molten alloys under anti-drossing conditions. To do so, I meltthe alloy in a kettle situated near the pipe press and run the moltenmetal thru an iron pipe to the top of the cylinder.

10 There the delivery pipe bends and extends down 15 0 c., above itsmelting point.

As the pipe leaves the press die, I prefer to pass it directly. thru agas expansion chamber or a cooling-liquid chamber mounted on the exitend of the press cylinder. And cool the pipe at such a m rate that it iswell below its meltingpoint as it reaches the outside atmosphere. I findthat this treatment restrains crystal growth.

I prefer to make my alloys by melting the minor constituents togetherunder nonoxidizing conditions and then adding these molten to the moltenlead'at 100-1800 under conditions of good agitation and anti-drosslng,such as protecting the lead surface in the kettle with a blanket ofpowdered carbon. I

so I claim as my invention:

1. An alloy consisting of .01% magnesium, 25% to 1.25% tin, .01% to .10%,manganese, and the balance lead.

2. An alloy consisting of 0.01% to 0.10% magneslum. 0.25% to 1.25% tin;0.01% to 0.10%

. manganese. and the balance lead. said alloy being more resistant tochemical corrosion than the same alloy devoid of manganese.

EDWARD G. HOLIMAN.

